The present invention relates to a power source and more particularly to a circuit arrangement to provide a fixed voltage source in series with an arbitrarily chosen impedance of any magnitude and phase angle.
In the line interface circuit of a telephone switching system, it is often necessary to power the telephone line from a voltage source through some fairly large series impedance. The impedance may be real, reactive or a combination of the two. In an effort to reduce the cost of the line interface circuit, it is desireable to fabricate as much of the circuitry as possible on silicon integrated circuit chips. Thus, the voltage source may be integrated as a switching power converter. Large reactive impedances, on the other hand, cannot be integrated and large resistive impedances in series with the power converter output would dissipate too much power to integrate. Furthermore, it is desirable to substantially eliminate the power dissipation due to the series resistance because of the ever increasing cost of energy and the reduced system reliability due to excessive heat.